在经典Mie散射理论基础上,利用POWELL反演方法研究了小角前向散射激光测粒仪中输入折射率对测量结果的影响。对于输入折射率与待测颗粒实际折射率没有偏差的情况,数据处理导致的测量误差在0.002%之内；而对于两者存在偏差的情况,当输入折射率在(2.0,4.0)范围内时数据处理误差较小,输入折射率在(1.1,2.0)范围内时数据处理误差显然较大。从而得到结论：在测量过程中应尽可能输入与颗粒实际折射率一致的数值；当无法确知颗粒实际折射率时,比较可靠的办法是适当选择一个大于2.0的数值作为输入折射率进行数据处理。

Based on the classical Mie scattering theory, the influence on the measured results which is caused by the inputted refractive index in data processing of the small-angle forward scattering laser particle sizer is investigated by means of POWELL inversion algorithm. The error would be within 0.002% in the case that the inputted refractive index equals exactly the natural one of the measured particles. Otherwise, when the inputted refractive index is in the range of (2.0,4.0) the magnitude of the error would be much less than in the range of (1.1,2.0). So, it comes to the conclusion that the value of the natural refractive index should be inputted in data processing if possible and a value larger than 2.0 should be believably chosen as the inputted refractive index if the natural refractive index of the measured particles is unknown.